1. Field of the Invention
This invention relates generally to semiconductor products manufacturing, and, more particularly, to a method and apparatus for automated routing of semiconductor devices through reentrant processes.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today""s manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and therefore, require a number of inputs that are generally fine tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing locations that contain different control schemes.
One of the most important aspects of semiconductor manufacturing is overlay control. Overlay is one of several important steps in the photolithography area of semiconductor manufacturing. Overlay control involves measuring the misalignment between two successive patterned layers on the surface of a semiconductor device. Generally, minimization of misalignment errors is important to ensure that the multiple layers of the semiconductor devices are connected and functional. As technology facilitates smaller critical dimensions for semiconductor devices, the need for reduced of misalignment errors increases dramatically.
Generally, photolithography engineers currently analyze the overlay errors a few times a month. The results from the analysis of the overlay errors are used to make updates to exposure tool settings manually. Some of the problems associated with the current methods include the fact that the exposure tool settings are only updated a few times a month. Furthermore, currently the exposure tool updates are performed manually.
Generally, a set of processing steps is performed on a lot of wafers on a semiconductor manufacturing tool called an exposure tool or a stepper. The manufacturing tool communicates with a manufacturing framework or a network of processing modules. The manufacturing tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface to which the stepper is connected, thereby facilitating communications between the stepper and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script, which can be a software program that automatically retrieves the data needed to execute a manufacturing process. Often, semiconductor devices are staged through multiple manufacturing tools for multiple processes. Generally, a routing system within the APC framework transports semiconductor devices through a manufacturing area by searching for the next available manufacturing tool, which may not net the highest quality output.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
In one aspect of the present invention, a method is provided for automatic routing of semiconductor devices within a manufacturing area. Performance of a plurality of manufacturing tools is tracked while processing semiconductor devices. At least one optimal combination of the manufacturing tools is determined based upon the tracked performance of the manufacturing tools. A queuing system is implemented to attain the optimal combination of the manufacturing tools. A dispatch system is deployed in response to the queuing system for routing the semiconductor devices within the manufacturing area.
In another aspect of the present invention, an apparatus is provided for automatic routing of semiconductor devices within a manufacturing area. The apparatus of the present invention comprises: means for tracking performance of a plurality of manufacturing tools while processing semiconductor devices; means for determining at least one optimal combination of the manufacturing tools based upon the tracked performance of the manufacturing tools; means for implementing a queuing system to attain the optimal combination of the manufacturing tools; and means for deploying a dispatch system in response to the queuing system for routing the semiconductor devices within the manufacturing area.